Beam wander is an important effect when a beam propagates in atmospheric turbulence. A set of measurements of beam wander of collimated beam using CCD techniques are conducted under the sea surface environment in Yantai region, and the characteristics are analyzed based on the measured data. Results show that the beam wander is larger in the horizontal direction than in the vertical direction, and the amplitude in horizontal direction is between 5.25 mm and 10.69 mm, and in vertical varies from 4.45 mm to 8.59 mm for a 1.21 km optical path. The mean ratio between the standard deviation in two directions is 1.33, and is lower than the value in other environments. The difference between the beam wander in two directions reduces with the increasing propagation distance, and the ratio is larger in nigthttime than in daytime. The beam wander keeps stable at different times. In addition, atmospheric refractive index structure parameter is also analyzed during the test period.